Ligand Coordination Site-Directed Assembly of Copper(I) Iodide Complexes of ((Pyridyl)-1-pyrazolyl)pyridine

A series of ((pyridinyl)-1H-pyrazolyl)pyridine (pypzpy) ligands in which the pyrazolyl ring at 1- and 3-positions is modified by two 2-, 3-, or 4-pyridyl groups were prepared. Reaction of CuI with 2-(1-(pyridin-2-yl)-1H-pyrazolyl)pyridine (2,2′-pypzpy) in MeCN at room temperature or solvothermal reaction of the same components at 120 °C afforded one binuclear complex [{(2,2′-pypzpy)Cu}(μ-I)]2 (1). Treatment of CuI with 3-(1-(pyridin-2-yl)-1H-pyrazolyl)pyridine (3,2′-pypzpy) at room temperature or at 120 °C produced one-dimensional (1D) polymer [{Cu3(μ3-I)3}(μ-3,2′-pypzpy)]n (2) and one two-dimensional (2D) polymer [{Cu2(μ-I)(μ3-I)}2(3,2′-pypzpy)2]n (3), respectively. Similar reactions of CuI with 4-(1-(pyridin-2-yl)-1H-pyrazolyl)pyridine (4,2′-pypzpy) at room temperature or at 150 °C yielded one 1D polymeric complex [{Cu(μ3-I)}2(4,2′-pypzpy)2{Cu(μ-I)}2]n (4). Complexes [{Cu3(μ3-I)3}(μ-2,3′-pypzpy)]n (5), [(CuI)(μ-2,3′-pypzpy)]2 (6), [(Cu2I2)(3,3′-pypzpy)] (7), [(CuI)(4,3′-pypzpy)] (8), [{Cu(μ3-I)}2(μ-2,4′-pypzpy)2{Cu(μ-I)}2]n (9), [(CuI)(3,4′-pypzpy)] (10), and [(CuI)(μ-4,4′-pypzpy)]n (11) could be isolated by solution reactions or solvothermal reactions of CuI with 2-, 3-, 4-(1-(pyridin-3-yl)-1H-pyrazolyl)pyridine (2,3′-, 3,3′-, 4,3′-pypzpy), or 2-, 3-, 4-(1-(pyridin-4-yl)-1H-pyrazolyl)pyridine (2,4′-, 3,4′-, 4,4′-pypzpy). Compounds 1–11 were characterized by IR, elemental analysis, powder X-ray diffraction, and single-crystal X-ray crystallography. Complex 1 contains a normal [Cu(μ-I)]2 dimeric structure. Complexes 2 and 5 consist of a unique displaced staircase chain [Cu2(μ3-I)2]n. Complex 3 has a 2D network formed by linking chairlike [Cu2(μ-I)(μ3-I)]2 units with two pairs of 3,2′-pypzpy bridges. Complexes 4 and 9 have a rare 1D triple chain, in which one internal 1D ladder-like chain [Cu2(μ3-I)2]n is connected with two zigzag chains [Cu(μ-I)]n via 4,2′-pypzpy or 2,4′-pypzpy ligands. Compound 6 consists of two [CuI] units interconnected by two 2,3′-pypzpy ligands. Compound 11 contains a 1D chain assembled by monomeric [CuI] units and 4,4′-pypzpy ligands. The luminescence properties of 1–11 in solid state were also investigated at room temperature. These results offer an interesting insight into how the coordination sites of the pypzpy ligands do exert great impact on their coordination modes, the coordination spheres of the Cu(I) centers, the formation of the [CunIn] motifs and the topological structures of the final complexes.